The present invention relates to the production of alkylamines, and particularly to the reaction of monoolefins with ammonia, in the presence of an alkali metal amide catalyst.
Alkylamines having 1-3 alkyls, each with 2-6 carbons, substituted on ammonia are produced commercially by the reaction of an alkanol such as ethanol with either ammonia, a monoalkylamine or a dialkylamine. Since the alkanol is itself normally produced by hydration of an alkene, e.g. the hydration of ethylene to ethanol, the direct production of alkylamines from alkenes would save a step in most commercial operations. In addition, the direct production of alkylamines from alkenes would eliminate the production of water as a by-product, which must be separated from the product alkylamines.
Processes have been proposed for reacting monoolefins with ammonia, monoalkylamines or dialkyamines to produce product alkylamines without the formation of by-products. For example, B. W. Howk et al., in J. Am. Chem. Soc., vol. 76, pp. 1899-1902 (1954) disclose the reaction of ammonia or alkylamines directly with olefins such as ethylene at elevated temperatures and pressures (well above the 132.5.degree. C. critical temperature of ammonia) in the presence of metallic sodium, potassium or lithium, their hydrides or their amides. Temperatures in the range of 175.degree.-200.degree. C. and pressures above 400 atmospheres in the range of 800-1000 atmospheres are indicated. Conversions below 50 percent for reactions with ammonia are indicated under these conditions. Higher conversions are reported for reactions of alkylamines with olefins with similar conditions. The authors support the theory that the reaction proceeds through an anionic mechanism.
For the related reaction of alkylamines with olefins, U.S. Pat. No. 2,750,417 to Closson et al (1956) teaches broadly that inorganic as well as organic amides of alkali metals may be used. Without actual examples other than of sodium amide, this references suggests that the other alkali metal amides (lithium, potassium, rubidium and cesium amides) would also work for this reaction.
U.S. Pat. No. 3,412,158 to McClain (Nov. 19, 1968) discloses the reaction of ethylene with ammonia in the presence of a Group VIII metal catalyst in the vapor phase at a temperature between 90.degree.-175.degree. C. and at a pressure between atmospheric and 2000 psi (100-14,000 kPa), and especially between atmospheric and 100 psi (100-800 kPa). None of these processes, nor any other process using the monoolefin directly, has appeared to supplant the alkanol reaction in commercial operations.
Mixtures of sodium amide and potassium amide are described as having melting points below that of either component, with a 1:2 molar eutectic being disclosed to melt at about 90.degree. C. in J. American Chem. Soc. vol. 45, page 712 (1923).